The present invention relates to bi-directional overrunning clutches for vehicles and more particularly to such a bi-directional overrunning clutch used in a front hub portion of a four wheel drive vehicle.
In a two wheel drive running condition of a four wheel drive vehicle, a wheel not driven, for example the front wheel, is driven from the road surface by contact thereof with the road surface. In this condition, since the driving force or rotation of the wheel is also transmitted to various mechanisms ancillary to the front wheel, i.e. mechanisms employed for a four wheel running mode, the running efficiency is decreased by the resistance of bearings and of oil. In order to improve such efficiency, means need be provided for limiting the driving force received from the road surface to the wheel and preventing transmission thereof to such other mechanisms.
It is therefore an object of the present invention to provide a bi-directional overrunning clutch which in a two wheel running condition can limit the driving force which is received by a non-driven wheel from the road surface to that wheel only.
It is a further object of the present invention to provide a bi-directional overrunning clutch in a four wheel drive condition can effectively transmit the driving force of the drive shaft to the drive wheel.
It is another object of the present invention to provide a bi-directional overrunning clutch for a four wheel drive which can offer an extremely high running efficiency.